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System Advisor Model (SAM)

Accounting for Daylight Saving Time (DST) in electricity rates

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grmiller
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30 Dec 2021 00:12 - 30 Dec 2021 23:00 #10443 by grmiller

Accounting for Daylight Saving Time (DST) in electricity rates was created by grmiller

Hi SAM team,

I understand that SAM generally does not make any adjustments for DST in the results, that is, all results are presented in local standard time. However, I would appreciate some clarification on how this applies to entering time of use electricity rates, and how this affect results that depend on the prevailing local time, such as energy demand and battery dispatch.

I am using the SAM PV-Battery model in SAM 2021.12.2, and attempting to simulate optimal economic dispatch of BTM residential batteries based on a local TOU electricity rate, which has a peak energy pricing period from 4pm - 9pm, year round. Since SAM does all of its calculations in standard time, I'm wondering if I need to shift the peak period to 3-8pm from March - October (when DST is in effect), since this represents the prevailing 4-9pm peak period in standard time.

Would the correct implementation of this rate (if 2 and 4 are the evening peak periods in the winter and summer, respectively, be:

(A) where we enter the rates in prevaling time, or

(B) where we keep all of the rates in local standard time?

Last edit: 30 Dec 2021 23:00 by pgilman.

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pgilman

30 Dec 2021 23:07 #10448 by pgilman

Replied by pgilman on topic Accounting for Daylight Saving Time (DST) in electricity rates

Hi Greg,

Images do not work very well when you paste them into the forum editor. It is best to attach image files to your post and then insert them into your message.

Anyway, SAM makes several assumptions about time:

The first time step of the simulation is in the first hour of Monday, January 1 (regardless of the year time stamp in the weather file).
Weekdays are Monday - Friday, weekends are Saturday and Sunday.
Times are in local standard time given the time zone in the weather file. There is no adjustment for daylight savings time.
There is no February 29, even in a leap year.

So, yes, if you wanted to be as accurate as possible, you would shift the times in the weekday/weekend schedules for time-of-use periods that fall during daylight savings time.

Best regards,
Paul.

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